The disclosure of Japanese Patent Application No. 2000-233692 filed on Aug. 1, 2000, including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to an apparatus and method for determining a state of a power train having a power transmission apparatus provided on the output side of a driving power source.
2. Description of Related Art
In general, a driving power source is mounted on a vehicle, and a power train is configured so as to transmit the power of the driving power source to the wheels via a power transmission apparatus. Japanese Laid-Open Patent Publication No. 10-196427 describes an example of a controller of a vehicle having such a power train.
The aforementioned publication describes a hybrid vehicle having a plurality of driving power sources, specifically an internal combustion engine and a motor generator. A first clutch is provided in a power transmission path from the engine to a transmission, and a second clutch is provided in a power transmission path from the motor generator to the transmission. A battery is connected to the motor generator through an inverter. When both the engine and the motor generator operate normally, the first and second clutches are engaged/disengaged based on a predetermined normal control mode, and the vehicle runs with the power of at least one or both of the engine and the motor generator.
If at least either the engine or the motor generator fails, a failure control mode different from the normal control mode is selected. In this mode, whether the engine has failed or not is determined based on the fuel injection amount, throttle valve opening, engine speed, and the like. Whether the motor generator has failed or not is also determined based on the revolution speed of the motor generator, road friction coefficient, vehicle speed, and the like. If it is determined that the engine is not operating normally and the failure control mode is selected, the vehicle runs with the motor generator as a driving power source. On the other hand, if the motor generator has failed, a control is carried out in which the vehicle runs with the engine as a driving power source.
The driving controller of the aforementioned publication determines whether or not there is a failure in each driving power source itself based on the information such as revolution speed of the driving power source, but does not recognize any failure that may have occurred in the power transmission apparatus coupled to the output side of the driving power source, e.g., clutch and brake. This results not only in an inability to determine whether or not there is a failure in the power transmission apparatus, but also requires the provision of a special (dedicated) failure determination apparatus in order to determine whether or not there is such failure. Accordingly, further improvement is possible in this respect.
It is one object of the invention to provide an apparatus and method for determining a state of a power train, which is capable of determining, with an existing system, a failure in a power transmission apparatus coupled to an output side of a driving power source, without the need for a special failure determination apparatus.
In a first aspect of the invention, an apparatus for determining a state of a power train that is configured to transmit power of a first driving power source to an input side of a second driving power source via a power transmission apparatus, and is capable of controlling a power transmission state of the power transmission apparatus, determines the power transmission state of the power transmission apparatus based on a physical quantity associated with a revolution speed of the first driving power source and information indicating a state of the second driving power source.
According to one implementation of the aforementioned aspect, the state of the power transmission apparatus is determined based on the revolution speed of the first driving power source and the revolution speed of the input side of the second driving power source. Accordingly, the revolution speed of the first driving power source and the revolution speed of the input side of the second driving power source can be utilized as information in a wider range of applications than previously used, and the need for a special (dedicated) failure determination apparatus for determining the state of the power transmission apparatus is eliminated.
In the aforementioned aspect, the power transmission apparatus may include a clutch and a transmission, and a determination can be made, when either the clutch or the transmission has a normal power transmission state, regarding a power transmission state of the other, based on the physical quantity associated with the revolution speed of the first driving power source and the information indicating the state of the second driving power source.
Thus, assuming that either the clutch or the transmission operates normally, the power transmission state of the other is determined based on the physical quantity associated with the revolution speed of the first driving power source and the information indicating the state of the second driving power source. Accordingly, accuracy of determining the power transmission state of the clutch or the transmission is improved.
In the aforementioned aspect, examples of the power transmission states of the power transmission apparatus include whether or not there is a failure (abnormality) in which the torque capacity or gear ratio is incapable of being controlled, whether or not there is a failure in which the gear ratio is not able to be set, progress or transitional state in changing the torque capacity or gear ratio, and the like.
In the aforementioned aspect, examples of the physical quantities associated with the revolution speed of the driving power source include the revolution speed itself of the driving power source, as well as the state of an apparatus for controlling the revolution speed of the driving power source, e.g., a throttle opening amount, etc.
In a second aspect of the invention, an apparatus for determining a state of a power train includes a driving power source, a power transmission apparatus coupled to an output side of the driving power source, and a controller that determines a failure in the power transmission apparatus based on a revolution speed of the driving power source.
In one implementation of the second aspect, a failure in the power transmission apparatus is determined based on a physical quantity associated with the revolution speed of the driving power source. Accordingly, the revolution speed of the driving power source can be utilized in a wider range of applications than previously used, i.e., as information other than that for controlling the driving power source, and the need for a special (dedicated) failure determination apparatus for determining the state of the power transmission apparatus is eliminated.
In the second aspect, the power transmission apparatus may include a clutch and a transmission, configured to transmit power of the driving power source to the transmission via the clutch, and the controller may determine, when either the clutch or the transmission operates normally, a failure in the other, based on a physical quantity associated with the revolution speed of the driving power source.
Thus, assuming that the clutch operates normally, a failure in the transmission is determined based on the physical quantity associated with the revolution speed of the driving power source. Accordingly, accuracy of determining a failure in the transmission is improved.
In the aforementioned aspect, the controller may determine that a failure has occurred, when the clutch operates normally and the revolution speed of the driving power source does not correspond to a revolution speed corresponding to a prescribed gear ratio that is set by the transmission, the determined failure being one in which the gear ratio of the transmission is incapable of being set to the prescribed gear ratio.
Thus, provided that the clutch operates normally, if the revolution speed of the driving power source does not correspond to the revolution speed corresponding to the prescribed gear ratio that is set by the transmission, it is determined that the failure in which the gear ratio of the transmission is incapable of being set to the prescribed gear ratio has occurred. Accordingly, a failure in the transmission can be determined specifically.
In the aforementioned aspect, the controller may determine that a failure has occurred, when the clutch operates normally and the revolution speed of the driving power source does not correspond to any one of the revolution speeds respectively corresponding to all of the gear ratios that are set by the transmission, the determined failure being one in which a gear ratio thereof is unable to be set to any one of the gear ratios.
Thus, provided that the clutch operates normally, if the revolution speed of the driving power source does not correspond to any one of the revolution speeds respectively corresponding to all of the gear ratios that are set by the transmission, it is determined that the failure in which the gear ratio of the transmission to any gear ratios is unable to be set has occurred. Accordingly, a failure in the transmission can be determined specifically.
In the aforementioned aspect, the controller may determine that a failure in which the gear ratio of the transmission is incapable of being changed has occurred, when the clutch operates normally and the revolution speed of the driving power source does not change in response to a request to change the gear ratio of the transmission.
Thus, provided that the clutch operates normally, a gear change request is generated to change the gear ratio of the transmission, and if the revolution speed of the driving power source does not change, it is determined that the failure in which the gear ratio of the transmission is incapable to be changed has occurred. Accordingly, a failure in the transmission can be determined specifically.
In the second aspect, a failure in either the clutch or the transmission is determined based on information other than the revolution speed of the driving power source.
In the first and second aspects, the power transmission states of the power transmission apparatus include, for example, a torque capacity transmitted between an input-side rotating member and an output-side rotating member of the power transmission apparatus, and a ratio between the revolution speed of the input-side rotating member and the revolution speed of the output-side rotating member of the power transmission apparatus, i.e., a gear ratio. A failure in either the clutch or the transmission may be determined based on information other than the revolution speed of the first driving power source and the revolution speed of the second driving power source.
Further, in the first and second aspects, examples of failures include a failure in the power transmission apparatus (transmission, clutch) itself, a failure in an actuator for controlling the power transmission state of the power transmission apparatus, and a failure in a signal system of a detector for detecting a request to control the power transmission state. Still further, in the first aspect, the information indicating the state of the second driving power source includes a physical quantity associated with the revolution speed of the input side of the second driving power source, e.g., the revolution speed itself, as well as a state of an apparatus for controlling that revolution speed.
Other aspects of the invention relate to methods of determining the state of a power train as described above.